Introduce a new unknown p = .
Then = , and your equation takes the form
= .
Factor left side. You will get
(p-1)*(p-2) = 0.
The roots are p=1 or/and p=2.
Since p = , it means that
= 1 (1)
or/and
= 2. (2)
Raise 1) and (2) into degree 4. you will get the solutions of the original problem
x = 1 or/and x = = 16.
Answer. x = 1 or/and x = 16.